DE2131377B2 - Nuclear reactor with emergency cooling system - Google Patents

Description

Gap 7 opening inlet, one in the lower part of the moderator vessel 5 opening under the core bottom 4 and an outlet arranged in the pump housing and the pump impeller 12 driven by the pump shaft. The reactor pressure vessel 6 is in the lead-through area 13 of the pump shaft reinforced locally.

Inside the ring of circulating pumps go through the bottom part of the reactor pressure vessel 6 multiple vertical controls 14. only one of which is shown. Each control organ consists of one Control rod 15 and a drive element 16 for the control rod. The control rod runs under the core 2 in a control rod pipe 17, the top with a Kassettenabstellplalte 18 (see Fig. 3) for four square arranged Brenns! Mkassetten 3 provided is. between which there is a cruciform gap 19. The control rod shown can be in this gap 15, which also has a cruciform cross-section, can be moved.

The cassette shelf 18, which is square in cross section, has four at the corners one Round holes 20 arranged in squares for receiving the lower ends of fuel assemblies and a central cross-shaped hole 21 for the control rod 15 to pass through. The cassette shelves 18 together form the core base 4.

The upper part of the control rod pipe 17 has four symmetrical impressions 22 (Fig. 4), on which the round cross-section of the tube on the cassette storage plate 18 into a cross-shaped cross-section transforms. As a result, the cooling water located outside the guide tube 17 is in the fuel assemblies guided upwards, while the water in the guide tubes 17 in the gap 19 between the fuel assemblies is directed upwards. The control rod pipe 17 expediently consists of three Parts, namely an upper part 23, which can be formed in one piece with the cassette storage plate 18 can u ^ d the indentations 22, a straight, circular cylindrical intermediate part 24 and a lower transition part 25, which is from einsm control member tube 26 is carried, which goes through the bottom of the reactor pressure vessel 6 and on this in one inwardly directed nozzle 27 (Fig. 4) is attached.

The control rod tube 17 has at its lower end an annular distribution chamber 27, of which four distribution tubes 28, namely one for each of the fuel assemblies carried by the guide tube, lead upwards and open directly or indirectly at the lower ends of the fuel assemblies 3.

The emergency cooling water is normally heated in a heating coil 45 Reserved container 29, which according to F i g. 1 are pressurized by means of gas from gas cylinders 36 can. The gas is thereby from the gas bottles through a line 30 with a normally open Test valve 31 and a normally closed emergency cooling valve 32 into the water tank 29 from above directed. The pressurized emergency cooling water leaves the container through a main line 33, flows through a cooling water nozzle (not shown) into the reactor, is distributed over branch lines 34 to the various distribution chambers 27 and flows from there via the distribution pipes 28 to the lower ends of each fuel assembly.

Fig.?. shows that the main line 33 is divided into several Branch lines 34 can be divided, the outside of the reactor pressure vessel 6 to the control organ tubes 26 are connected. The control member tube 26 is double-walled so that between his Walls 26 'and 26 "an annular gap 35 remains. As can be seen in more detail from FIG. 4, connects the gap 35 the annular distribution chamber 27 with branch line 34.

The distribution pipes 28 leading from the distribution chamber 27 go out, run through the lower one

ίο transition part 25 to the inside of the control rod tube 17 and through the upper part 23 to the outside of the control rod tube 17. As shown in FIG. 4, the distribution pipes 28 can open either directly under the lower ends of the fuel assemblies 3 or also indirectly. In the latter case, each distribution pipe opens into an annular groove 37 on the underside of which is arranged in the circular supporting hole 20 throttle plate 36. From the annular groove 37, the emergency core cooling water by means of several inwardly-upwardly dishes' · .. holes 41 becomes a Urd between the throttle disc the area located at the bottom of the fuel assembly. The throttle disk has the shape of a conventional measuring orifice and is held in the desired position by means of several axial spring tongues 38 extending from the circumference of the disk, each spring tongue 38 being provided with a holding part 39 which is inserted into an annular groove 40 arranged in the hole 20 intervenes.

The emergency cooling valve 32 opens on the basis of a signal from a control unit 42 of a type known per se. The control unit decides on the basis of the incoming measured values whether emergency cooling is triggered should be or not. In Fig. 1 is just one of a neutron flux probe in the core to the control unit leading signal line 43 indicated as well as one leading from the control unit to the emergency stop valve Signal line 44.

The gas contained in the gas bottles 36 can

<o z. B. nitrogen at a pressure of about 200 bar be. If it is to be feared that the system could be emptied so far from water in the case of emergency cooling, that gas penetrates the reactor, it is advisable to use a mixture of nitrogen and hydrogen, the hydrogen content should be about 5%> in order to achieve both oxygen fixation on the Nitrogen in the reactor and the resulting formation of nitric acid as well as a risk of explosion to be avoided when mixing with air.

The test valve 31 can be arranged in the line 30 before or after the emergency cooling valve 32 and is used to check the function of the emergency cooling system during operation. The valves 31 and 32 are conveniently close to one another so that the connecting tube 30 is short. At a Test, the test valve 31 is closed first, a position indicator indicating that the valve closed is. Then the emergency cooling valve 32 is opened and closed again, with a second Position indicator shows that opening and closing are actually being carried out. Finally will the test valve 31 is opened again, its position indicator confirming that the opening is taking place is. Because the tube 30 connecting the valves is short, the volume of gas enclosed therein is with high pressure small, which has the consequence that only a very small part of the emergency cooling water during a test from the water tank 29 into the reactor 1

int. After the test, the low (lasge, located in the container can be vented through a valved conduit shown in it. The water tank is completely filled with water from the reactor again

During the air flow, the water tank 2'J and gas bottles 16 can be replaced by other means with a corresponding effect. One can ι. U. when an emergency cooling is triggered, the emergency cooling water can be taken from an IJassin for used fuel and pressurized using a pump. The cooling water can also be stored under pressure in one or more Diuckakkunuilatoren.

I Hlat! drawings

Claims (1)

1 2 French patent specification 1 490 229) is for emergency cooling Claim: an additional steam circuit is provided with which Cooling steam directly in the reactor core Nuclear reactor with a pressure vessel that will conduct one. Like the distribution of the coolant in the Floor, a 5 reactor core arranged in the reactor pressure vessel is made from the Core with several vertical fuel assemblies. th patent specification cannot be seen. The drawing of the several vertical control rod pipes. the patent specification shows no vertically arranged control from the core down to the bottom of the pressure rods or control rod pipes. In the additional extend the vessel, as well as means for the emergency circuit, at least one heat exchanger is connected. Cooling (emergency cooling means) of the reactor core is ordered, which extracts heat from the cooling steam by injecting water into the same on- The invention has for its object to provide a has, with a feed line at the lower end of the nuclear reactor of the type mentioned above. of the reactor vessel opens into this and means that form water intended for emergency cooling are provided for the supply of cooling water, with the least possible disruption of normal flow characterized in that the emergency t ₅ regulations in the reactor directly introduced into the core coolant (27 to 35) can be at the lower end. This object is achieved according to the invention leüungskammer (27) and solved from this starting that the emergency cooling means one at the bottom have upwardly conductive distribution pipes (28). At the end of each control rod tube the distribution pipes (28) directly or indirectly 20 dividing chamber and starting from this upwards have conductive distribution pipes on the lower lid of a fuel assembly (3), the openings divider pipes directly or indirectly at the lower end open into a fuel cassette. Since the Not-15 coolant flows in the same direction as The invention relates to a nuclear reactor, the normal coolant, one gets a cheaper one with a pressure vessel that has a bottom, one in the flow pattern, creating a more even and Reactor pressure vessel arranged core with several more effective cooling than previously achieved. the vertical fuel assemblies, several vertical distribution pipes direct the cooling water directly into Control rod pipes extending from the core down 30 the fuel assemblies, which is particularly effective extend to the bottom of the pressure vessel, and allows heat dissipation because the heat in place Means for the NoUuhlung (emergency coolant) of their creation directly absorbed by the coolant Reactor core by injecting water into it. same, wherein a is at the bottom to ^f ührleitung An embodiment of the invention post- End of the reactor vessel in this mf idet and means ₃₅ explained in more detail below with reference to the drawings, are provided for the supply of cooling water. It shows It is of the utmost importance that the kernel in FIG. 1 schematically the lower part of a reactor is effectively cooled, especially in a reactor provided with an emergency cooling system,
various emergencies such as B. with a break in Fig. 2, a variant for the supply of the emergency primary circuit of the coolant. With water-cooled ₄₀ cooling water to the reactor, A large part of the cooling water Fig. 3 goes from above two adjacent reactors lost as steam and must be replaced. After cassette mounting plates, each of which is at the top an earlier proposal is the core of a boiling end of a control rod tube and with four Wasserreaktors emergency cooling water from above through nozzles arranged round the corners of a square is provided in a double-walled lid of the core environmentally ₄₅ holes, the lower ends of four given moderator vessel, d. H. To accommodate fuel assemblies and a central in a direction corresponding to the direction of the normal i _es cross-shaped hole for the control rod Cooling water flow is opposite. In this case corresponds _an d there is an unstable flow, since in large parts F i g. 4 in a partial axial section after the line of the core warm water and steam upwards ₅₀ IV-IV in F i g. 3 two adjacent control risers, while in other parts of the core cold stableitube with distribution chamber and distribution water sinks downwards. raw. en for the emergency cooling water. In a known nuclear reactor of the type initially shown in FIG. The reactor 1 shown in FIG. 1 is a boiling type (French patent 1,570,268) water reactor. The reactor core 2 is, as usual, from the emergency core cooling water is built directly into the pressure ₅₅ fuel rods, the fuel assemblies to container 3 introduced and are indeed composed depending on, only two of which angedeudem prevailing in the reactor vessel water level. were switched. The fuel assemblies have a qua-If this has fallen below a predetermined dimension, dratic cross-section and are of a core, the supply of emergency cooling water in the corridor floor 4 is gertagen. The core is of a fashion set. To supply the emergency cooling water, a 60 gate vessel 5 is surrounded, which in turn is provided by a reactor turbine-driven pump, which is surrounded with the aid of gate pressure vessel 6 in such a way that a tubular, vertical gap 7 is operated between the steam vessels S and 6 discharged from the reactor vessel. This is intended to provide the cooling water supply. In the lower part of the gap several are independent of an external energy source. Reactor-internal circulating pumps 8 arranged, of which only one is shown via a direct introduction of emergency cooling 65. Each pump has a water in the reactor core is nothing to be found in the aforementioned fianzö- outside the reactor pressure vessel arranged sischen patent. Motor 9, a vertical pump shaft 10, a pump-In another known nuclear reactor (French housing 11 with a curved passage, one in the